Overheating on the Turbo II
 

I have a problem with my 1988 Rx-7 Turbo II. The car originally had an overheating (got hot, but never into the red zone) problem due to the main core heater hose splitting and there being a huge loss of coolant fluid. It technically never overheated but it did get quite hot. I had this problem repaired, my fluids replenished and now it still overheats. A rotary specialist said they think it's due to the inner coolant o-ring going bad in the engine since it seems I am now burning up coolant fluid (i think there is some whitish smoke coming from my exhaust). Well, the engine now attempts to overheat constantly and I can't drive it for any more than 5 minutes. The engine has 133000 miles on it and 21000 miles on the rebuild/street-port. Could this all be related to what the rotary specialists told me or could it possibly be a different problem? I was quoted for $2700 to repair the engine. I thought that was a little too much, so I would be thankful for any help whatsoever. In fact, if anyone knows a rotary specialist willing to guide me to repairing this myself, I would like to be notified of that person. I live in Chesapeake, Virginia and I'm willing to pay for some assistance.

See http://www.aaroncake.net/rx-7/cooling.htm for cooling system troubleshooting.

But if you are burning coolant, then you need a rebuild regardless. And depending on how long this has been happening and how much damage occurred, many of your internal engine parts can be unusable.

Yes, sounds like it is definitely a coolant seal. The rotary is an iron aluminum block, and the seals are in between each part; think of them as large rubber bands. When you start running higher temperatures the 2 metals expand at different rates, and the seals are compromised...usually they get broken in one spot due to the pressure, and from then on they don't seal in that spot. This is similar to a headgasket blown on a piston engine. There is also the possibility that you cracked an iron water jacket (it's a very thin casting that holds the seals in place) which is more similar to a cracked head...it requires replacement of that part and possibly others.

As for the rebuild, if it's installed, thats about industry standard considering you might need a few hard parts replaced during the rebuild (in addition to standard soft seals). I can probably get you in for closer to $2000 installed, depending on the condition of your internals. But you're quite a ways away though so I dont know of that's an option.

Solid symptoms of coolant seal failure are :

1) excess pressure in the coolant system while running and shortly after shutdown...swelled hoses, blowing the tops off of radiators, etc.

2) white smoke at startup...coolant being converted to steam inside the engine as combustion occurs.

3) Bubbles and air in the coolant system when the cap is removed...sometimes producing a guyser effect...combustion pressure pushes coolant out of the system into the overflow constantly.

4) you crank the engine a second or 2 and then remove the plugs, only to find water droplets on one or more of them.

5) you cannot seem to keep the coolant full, yet cannot find an external leak.

6) hard starting when warm after sitting for a couple of minutes...water seeps into the combustion chamber and floods it.

Thanks. I think I definitely know what's the problem now. It has to be a coolant seal that broke. If someone can find me the o-rings at a reasonable price, that would be great.

Uhm...you don't replace just those. You have to tear the engine completely down to get to them...you're a fool if you dont replace at least your apex seals and oil seals at the same time...last time I checked, this was called a rebuild.

Well, I know a place that can hook me up with the seals, it's just that the o-rings seem to be the harder item to get. But yes, I know this is a rebuild. In fact I got the car to the point where I am about to lift the engine out the car.

^right on.

Like RR said, if I were you, I'd definitely consider buying more that just the internal coolant seals. While your at it (depending on your budget) you might as well replace what you can. Maybe take advantage of the situation and street-port the motor? (that is unless you don't like going fast ;))

his motor is already streetported..

anyways, i was going to suggest pressure checking the system before condemning it but i guess it's too late for that... sometimes coolant can leak externally in obscure areas that do not necessarily show up easily on the ground.

but since you already are this far you may as well pull it and rebuild it.